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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

27396 results found.

  1. GRB 050408: Swift XRT analysis
  2. GRB 050408: Optical limit at 20 min after the burst
  3. GRB050408: REM NIR and Optical observation
  4. GRB 050408,optical observation
  5. GRB 050408: Mercator Optical Observations
  6. GRB 050408: Optical afterglow confirmed
  7. GRB 050408: opitcal observation
  8. GRB 050408, optical observations
  9. GRB 050408 optical candidate
  10. GRB 050408: Swift XRT Position
  11. GRB050408: MASTER optical observations
  12. GRB050401: Radio Detection
  13. GRB 050406: early Swift XRT analysis results
  14. GRB 050406 BAT refined analysis
  15. GRB 050406: Early observations with Swift-UVOT
  16. Swift-BAT detection of GRB 050406
  17. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  18. GRB 050401: VLT spectroscopic redshift
  19. GRB 050401 BAT refined analysis
  20. GRB050401: TNG R-band observation
  21. GRB 050402: Early observations with Swift-UVOT
  22. Swift Trigger 113225: P60 Observations
  23. GRB 050401: Optical afterglow confirmed
  24. GRB 050401: Prompt XRT position
  25. Retraction of three Swift GRB triggers
  26. GRB050331: No Afterglow Detected
  27. Swift-BAT detection of GRB 050331b
  28. GRB 050331: Swift UVOT Source
  29. Swift-BAT detection of GRB 050331
  30. GRB 050326: Early observations with Swift-UVOT
  31. GRB 050326 XMM-Newton observation
  32. GRB 050326: Swift XRT Position
  33. GRB 050326 BAT refined analysis
  34. GRB050326: delayed XRT observation
  35. GRB050319, color indices
  36. GRB050319: optical observation, March 20-22
  37. GRB050319: RTT150 Optical Observations
  38. Swift-BAT trigger 112060 is not a real GRB
  39. GRB 050318: Swift-BAT refined analysis
  40. GRB050319: VLA Observations
  41. GRB050319: radio observation
  42. GRB 050319: Swift-UVOT detection of the afterglow
  43. GRB 050315: Variability Analysis of Swift BAT Time History
  44. GRB050319: Radio Observations
  45. GRB 050319: NIR afterglow candidate
  46. GRB 050319:Near IR afterglow
  47. GRB 050318: SWIFT-UVOT refined analysis
  48. GRB 050319 : Confirmation of optical afterglow decay
  49. GRB 050319: Swift-BAT refined analysis
  50. GRB050319,optical observation
  51. GRB 050318: Swift/UVOT detection of afterglow emission
  52. RXTE Observations of GRB050318
  53. GRB050223: analysis of the XMM-Newton observation
  54. GRB050316: MASTER before, simultanious and follow up optical
  55. GRB 050306: ROTSE-III early limits
  56. GRB050316: MASTER optical observations
  57. GRB 050315: Swift-BAT further refined analysis
  58. GRB 050315 I-band observations
  59. GRB050315: Radio afterglow
  60. GRB050315: Swift-BAT Refined analysis
  61. Non-detection of GRB050315 in ATCA Radio Observations
  62. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  63. GRB 050315: Early Observations with Swift/UVOT
  64. GRB 050306: Radio Observations
  65. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  66. GRB 050306: optical afterglow
  67. Swift-BAT trigger 107873: No Swift XRT counterpart
  68. GRB 050306: Confirmation of X-ray afterglow
  69. GRB 050306: further TAROT optical data
  70. GRB050309: Early optical limit from P60
  71. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  72. GRB 050309 : Lulin R-band observation
  73. Swift 107873: P60 Optical Observations
  74. GRB 050306: R-band observations
  75. GRB 050306: REM optical-infrared observations
  76. GRB 050306: Possible X-ray Afterglow Position from the Swift
  77. GRB 050306: TAROT optical observations
  78. GRB 050306,optical observation
  79. Ongoing activity of SGR 1806-20 after the giant flare
  80. GRB050215B: Late-Time Swift UVOT Observations
  81. PROMPT VRcIc Observations of GRB 050223
  82. XRF/GRB 050215B: Radio Observations
  83. XMM-Newton Images of GRB 050223
  84. GRB 050219b: candidate NIR afterglow
  85. Confirmed XRF nature for GRB050215b
  86. GRB050223 XMM-Newton observation
  87. INTEGRAL detection of GRB 050223
  88. GRB050223: ROTSE-III Optical Observations
  89. GRB 050223 Swift/BAT detection of a burst
  90. GRB 050223: Swift XRT Position
  91. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  92. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  93. GRB 050219a: Optical observations from LCO
  94. GRB 050219b: Optical and near-IR observations from LCO
  95. GRB 050219b: Swift-BAT detection of a burst
  96. GRB 050219b: CORRECTION: Swift XRT Position
  97. GRB 050219b: Swift XRT Position
  98. GRB 050219: Swift-BAT detection of a burst
  99. GRB 050215b: XRT confirmation of IR afterglow candidate
  100. GRB050215b: P60 Optical Observations

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